Academic literature on the topic 'Two-temperature theory'
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Journal articles on the topic "Two-temperature theory"
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Youssef, H. M. "Theory of two-temperature-generalized thermoelasticity." IMA Journal of Applied Mathematics 71, no. 3 (June 1, 2006): 383–90. http://dx.doi.org/10.1093/imamat/hxh101.
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Orlac’h, Jean-Maxime, Vincent Giovangigli, Tatiana Novikova, and Pere Roca i Cabarrocas. "Kinetic theory of two-temperature polyatomic plasmas." Physica A: Statistical Mechanics and its Applications 494 (March 2018): 503–46. http://dx.doi.org/10.1016/j.physa.2017.11.151.
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Sur, Abhik, and M. Kanoria. "Three-Dimensional Thermoelastic Problem Under Two-Temperature Theory." International Journal of Computational Methods 14, no. 03 (April 13, 2017): 1750030. http://dx.doi.org/10.1142/s021987621750030x.
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The present paper deals with the problem of thermoelastic interactions in a homogeneous, isotropic three-dimensional medium whose surface suffers a time dependent thermal loading. The problem is treated on the basis of three-phase-lag model and dual-phase-lag model with two temperatures. The medium is assumed to be unstressed initially and has uniform temperature. Normal mode analysis technique is employed onto the non-dimensional field equations to derive the exact expressions for displacement component, conductive temperature, thermodynamic temperature, stress and strain. The problem is illustrated by computing the numerical values of the field variables for a copper material. Finally, all the physical fields are represented graphically to analyze the difference between the two models. The effect of the two temperature parameter is also discussed.
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Ezzat, Magdy A., Alaa Abd El Bary, and Ahmed S. El Karamany. "Two-temperature theory in generalized magneto-thermo-viscoelasticity." Canadian Journal of Physics 87, no. 4 (April 2009): 329–36. http://dx.doi.org/10.1139/p08-143.
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A one-dimensional model of the two-temperature generalized magneto-viscoelasticity with two relaxation times in a perfect conducting medium is established. The state space approach is adopted for the solution of one-dimensional problems for any set of boundary conditions. The resulting formulation together with the Laplace transform techniques are applied to a specific problem of a half-space subjected to thermal shock and traction-free surface. The inversion of the Laplace transforms is carried out using a numerical approach. Numerical results are given and illustrated graphically for the problem. Some comparisons have been shown in figures to estimate the effects of the temperature discrepancy and the applied magnetic field.
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Youssef, Hamdy M. "Theory of Two-Temperature Thermoelasticity without Energy Dissipation." Journal of Thermal Stresses 34, no. 2 (January 13, 2011): 138–46. http://dx.doi.org/10.1080/01495739.2010.511941.
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Ezzat, Magdy A., and Ahmed S. El-Karamany. "Two-temperature theory in generalized magneto-thermoelasticity with two relaxation times." Meccanica 46, no. 4 (August 5, 2010): 785–94. http://dx.doi.org/10.1007/s11012-010-9337-5.
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Mukhopadhyay, Santwana, Rajesh Prasad, and Roushan Kumar. "On the Theory of Two-Temperature Thermoelasticity with Two Phase-Lags." Journal of Thermal Stresses 34, no. 4 (March 9, 2011): 352–65. http://dx.doi.org/10.1080/01495739.2010.550815.
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Metens, T., and R. Balescu. "Relativistic transport theory for a two‐temperature magnetized plasma." Physics of Fluids B: Plasma Physics 2, no. 9 (September 1990): 2076–90. http://dx.doi.org/10.1063/1.859428.
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Chiku, S. "Optimized Perturbation Theory at Finite Temperature: Two-Loop Analysis." Progress of Theoretical Physics 104, no. 6 (December 1, 2000): 1129–50. http://dx.doi.org/10.1143/ptp.104.1129.
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El-Karamany, Ahmed S. "Two-Temperature Theory in Linear Micropolar Thermoviscoelastic Anisotropic Solid." Journal of Thermal Stresses 34, no. 9 (September 2011): 985–1000. http://dx.doi.org/10.1080/01495739.2011.601260.
Full textDissertations / Theses on the topic "Two-temperature theory"
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Proestos, Yiannis. "Two dimensional supersymmetric models and some of their thermodynamic properties from the context of SDLCQ." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1184890795.
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Madhavi, S. "Carrier Mobility And High Field Transport in Modulation Doped p-Type Ge/Si1-xGex And n-Type Si/Si1-xGex Heterostructures." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/294.
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Modulation doped heterostructures have revolutionized the operation of field effect devices by increasing the speed of operation. One of the factors that affects the speed of operation of these devices is the mobility of the carriers, which is intrinsic to the material used. Mobility of electrons in silicon based devices has improved drastically over the years, reaching as high as 50.000cm2/Vs at 4.2K and 2600cm2/Vs at room temperature. However, the mobility of holes in p-type silicon devices still remains comparatively lesser than the electron mobility because of large effective masses and complicated valence band structure involved. Germanium is known to have the largest hole mobility of all the known semiconductors and is considered most suitable to fabricate high speed p-type devices. Moreover, it is also possible to integrate germanium and its alloy (Si1_zGex ) into the existing silicon technology.
With the use of sophisticated growth techniques it has been possible to grow epitaxial layers of silicon and germanium on Si1_zGex alloy layers grown on silicon substrates. In tills thesis we investigate in detail the electrical properties of p-type germanium and n-type silicon thin films grown by these techniques. It is important to do a comparative study of transport in these two systems not only to understand the physics involved but also to study their compatibility in complementary field effect devices (cMODFET).
The studies reported in this thesis lay emphasis both on the low and high field transport properties of these systems. We report experimental data for the maximum room temperature mobility of holes achieved m germanium thin films grown on Si1_zGex layers that is comparable to the mobility of electrons in silicon films. We also report experiments performed to study the high field degradation of carrier mobility due to
"carrier heating" in these systems. We also report studies on the effect of lattice heating on mobility of carriers as a function of applied electric field.
To understand the physics behind the observed phenomenon, we model our data based on the existing theories for low and high field transport. We report complete numerical calculations based on these theories to explain the observed qualitative difference in the transport properties of p-type germanium and ii-type silicon systems. The consistency between the experimental data and theoretical modeling reported in this work is very satisfactory.
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Izzo, Maria Grazia. "High frequency dynamics of fluid binary mixtures." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3585.
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2008/2009This thesis is aimed to the study of dynamics in binary fluid mixtures by means of inelastic scattering spectroscopies. Nowadays the understanding of these dynamics is still unsatisfactory. In particular, any model is able to adequately describe collective dynamics beyond the hydrodynamic limit. In such a low momentum (k) and frequency () transfer limit, the collective dynamics is characterized by a single (adiabatic) longitudinal acoustic mode accounting for sound propagation. At frequencies above the hydrodynamics ones a transition towards a decoupled dynamic regime is expected. This is characterized by two distinct modes, namely the slow (low-) and fast (high-) sounds. The microscopic mechanisms driving such a transition, so as the related macroscopic quantities, are still unclear, even in an heuristic point of view. In this work the collective dynamics of neutral and ionic mixtures are investigated with the aim to shed light in this debated issue. He/Ne mixtures have been studied by means of Inelastic X-ray Scattering (IXS) spectroscopy. Exploiting the lack of kinematic limitations peculiar of this technique, the high frequency (>THz) dynamics has been analyzed from the mesoscopic up to the high-k range, where the dynamic response of the system can be described using the Impulse Approximation (IA). This kind of study is of particular interest for disparate mass mixtures, since inefficient kinetic energy exchanges between light and heavy particles taking place on very short time scales are expected to greatly influence the phenomenology of the aforementioned dynamic decoupling. The prototype ionic mixture, RbF, also, has been investigated by means of Inelastic Neutron Scattering (INS) spectroscopy. Ionic mixtures are particularly suited to investigate the role played by optic-like excitations (related to concentration fluctuations) in the transition from the hydrodynamics to the decoupled regime. Indeed, these kind of excitations are expected to be emphasized because of the long range Coulomb interactions. Conversely at k’s enough high, i.e. k>k* with k* dependent on the values of the electric conduction coefficient and the adiabatic sound velocity, they are expected to behave like neutral binary mixtures. The study of molten RbF has been, then, focused on the characterization of collective dynamics in the transition region, which is more difficultly accessible by IXS because of instrumental limitations. IXS data on He0.8Ne0.2 mixture have been analyzed using a generalization of the viscoelastic function, which, in our knowledge, has been applied for the first time to this purpose. This kind of data analysis permitted to extrapolate the partial dynamical structure factors related to He-He, Ne-Ne and He-Ne density fluctuations. The adiabatic and high frequency sound velocity as well as the relaxation time associated to each mixture component has been calculated from fitting parameters. The analysis of the extrapolated relaxation times permitted to define, in the probed range, two k-region depending on the behavior of such quantity. At the higher k probed the relaxation times of single components can be well described by the respective single specie collision time, indicating a complete dynamics decoupling. At lower k, conversely, the relaxation times show a deviation to respect the collisional times. The study of the same mixture in three different thermodynamic conditions, revealed a common k trend of the single component relaxation times once proper normalization, made by means of kinetic parameters, has been done. An empirical expression has then been proposed. The result can be interpreted in the framework of ‘two temperature theory’, based on the assumption that in disparate mass binary mixtures inefficient kinetic energy exchanges induce a two step process for the relaxation of density fluctuations towards the thermodynamic equilibrium. These processes are characterized by two distinct timescales: the intra-specie collision time, where each specie subsystem reaches a condition of ‘local’ equilibrium associated with a ‘local’ temperature and a characteristic time for the equilibration of the microscopic temperatures to the thermodynamic temperature trough inter-specie collisions. A further corroboration of the above picture has been found from the analysis of IXS spectra in the IA region, which allowed extrapolating the momentum distribution functions of the specie subsets. An anomalous behavior has been noticed on the He momentum distribution function, i.e. the apparent temperature associated to the momentum distribution is about 40 K higher than the macroscopic one. This striking result can be straightforwardly interpreted as a fingerprint of the peculiar ‘two temperature’ equilibration process. INS experiment on molten RbF permitted to reveal the simultaneous presence of two dispersive collective modes in the transition region. The dispersive behavior (linear with k) and the characteristic energies permitted to exclude an optic-like nature for both excitations. The performed data analysis permitted also to extrapolate the value of the electrical conduction coefficient, founding a quite low value as compared with typical values of molten salts. An estimation of k* for the studied system emphasize the possibility that at the probed k it may be isomorphous to a neutral mixture. The observed phenomenology can be thus interpreted in terms of double sound propagation phenomenon, observed in rarefied non-ionic gaseous mixtures. Finally, an alternative interpretation of these experimental results can be qualitatively provided within the frame of the generalized collective mode approach. In this case the high frequency mode is identified with the extension of the adiabatic longitudinal sound mode beyond hydrodynamic limit that, in analogy to what observed in several fluids, follows a linear dispersion with an associated sound velocity larger than the adiabatic one. The low frequency mode could instead be associated with a propagating kinetic mode related to energy fluctuations (heat waves). In conclusion, an extensive analysis of high-frequency dynamics in binary mixtures has been reported. Particular emphasis has been devoted to the study of the sound decoupling phenomenon manifesting beyond the hydrodynamic region. The experimental results indicate that such a phenomenon is manifested in both neutral and ionic disparate mass binary mixtures. It can be related to microscopic dynamics, e.g. thermalization effects related to the inefficient kinetic exchange between lighter and heavier particles.
XXI Ciclo
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Palmer, Stephanie E. "Order and disorder in two geometrically frustrated antiferromagnets." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342663.
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Leonardsson, Kjell. "Variation in age and size at maturation in two benthic crustaceans in the Gulf of Bothnia." Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 1990. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100708.
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The thesis deals with variation in age and size at maturation in Saduria entomon and Pontoporeia affinis along a depth gradient in the Gulf of Bothnia, Sweden. I have analysed at what sizes and ages animals should mature in relation to growth and mortality conditions. The thesis also deals with predator-prey interactions within and between the two species. The isopod Saduria entomon matured during winter at an age of three years at 5 m depth in the Norrby archipelago (63° 30'N, 19° 50'E). Males matured eariier and at larger sizes (27-48 mm) than females (23-36 mm). The offspring were released in early summer. The adult size increased with increasing depth. Outside the archipelago, at 125 m depth, the sexes reached a size of 84 and 54 mm respectively. No evidence for temporal restriction in the release of the young was found at the deep area. The species was shown to have a high capacity for cannibalism on small conspecifics, although the small ones have the potential to avoid aggregations of large conspecifics. The number of small conspecifics eaten was related both to the absolute and relative densities of the alternative prey Pontoporeia affinis. The cannibalistic behaviour have the potential to act as a stabilizing mechanism in the Saduria-Pontoporeia system. Fourhom sculpin (Myoxocephalus quadricornis) was the fish species of utmost importance as a predator on S.entomon, and it mainly preferred large specimens. The amphipod Pontoporeia affinis matured at an age of two years in the littoral zone and at a very deep (210 m) locality. Between these depths it mainly reached maturation at an age of three years. In some years in densely populated areas, they delayed reproduction another year and reproduced as four year old. The variation in age at maturation in P.affinis in relation to depth could be quantitatively predicted by maximizing fitness in the Euler-Lotka equation. The size variation at maturation in S.entomon could be qualitatively predicted by maximizing fitness in the Euler-Lotka equation. The general condition for a smaller size at maturity to be adaptive at high temperatures (i.e. shallow areas) is that mortality rate should increase faster than growth rate with increasing temperature. When mortality is higher in young stages than in older and larger ones the pattern is also predicted when growth increases faster than mortality. Small animals may prefer warmer habitats than large ones, because of the presence of a size dependent trade-off between temperature induced growth and mortality. More exactly, the optimum solution of the trade-off between growth and mortality in hazardous environments was suggested to approach maximization of the expression s(W+g)/W, where s is survival rate, W is body weight, and g is growth rate.Diss. (sammanfattning) Umeå : Umeå universitet, 1990, härtill 6 uppsatser
digitalisering@umu
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Johnston, Steven Sinclair. "Electron-phonon Coupling in Quasi-Two-Dimensional Correlated Systems." Thesis, 2010. http://hdl.handle.net/10012/5274.
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Over the past 20 years a great deal of progress has been made towards understanding the physics of the high-temperature (high-Tc) cuprate superconductors. Much of the low- energy physics of these materials appears to be captured by two-dimensional Hubbard or t-J models which have provided significant insight into a number of properties such as the pseudogap, antiferromagnetism and superconductivity itself. However, intrinsically planar models are unable to account for the large variations in Tc observed across materials nor do they capture the electron-phonon (el-ph) interaction, the importance of which a number of experimental probes now indicate.
This thesis examines the el-ph interaction in cuprates using a combination of analytical and numerical techniques. Starting from the microscopic mechanism for coupling to in-plane and c-axis polarized oxygen phonons, the theory of el-ph coupling is presented. The el-ph self-energy is derived in the context of Migdal-Eliashberg theory and then applied to understanding the detailed temperature and doping dependence of the renormalizations observed by Angle-resolved photoemission spectroscopy. The qualitative signatures of el- boson coupling in the density of states of a d-wave superconductor are also examined on general grounds and a model calculation is presented for el-ph coupling signatures in the density of states. Following this, the theory is extended to include the effects of screening and the consequences of this theory are explored. Due to the quasi-2D nature of the cuprates, screening is found to anomalously enhance the el-ph contribution to d-wave pairing. This result is then considered in light of the material and doping dependence of Tc and a framework for understanding the materials variations in Tc is presented. From these studies, a detailed picture of the role of the el-ph interaction in the doped cuprates emerges where the interaction, working in conjunction with a dominant pairing interaction, provides much of the materials variations in Tc observed across the cuprate families.
Turning towards numerical techniques, small cluster calculations are presented which examine the effects of a local oxygen dopant in an otherwise ideal Bi2Sr2CaCu2O8+δ crystal. Here, it is demonstrated that the dopant locally enhances electronic properties such as the antiferromagnetic exchange energy J via local el-ph coupling to planar local oxygen vibrations. Finally, in an effort to extend the scope of this work to the underdoped region of the phase diagram, an examination of the properties of the single-band Hubbard and Hubbard-Holstein model is carried out using Determinant Quantum Monte Carlo. Here focus is placed on the spectral properties of the model as well as the competition between the the antiferromagnetic and charge-density-wave orders. As with the small cluster calculations, a strong interplay between the magnetic and lattice properties is observed.
Books on the topic "Two-temperature theory"
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J, Hanna Gregory, and Hugh L. Dryden Flight Research Center., eds. Thermal modeling and analysis of a cryogenic tank design exposed to extreme heating profiles. Edwards, Calif: National Aeronautics and Space Administration, Dryden Flight Research Facility, 1991.
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J, Hanna Gregory, and Hugh L. Dryden Flight Research Center., eds. Thermal modeling and analysis of a cryogenic tank design exposed to extreme heating profiles. Edwards, Calif: National Aeronautics and Space Administration, Dryden Flight Research Facility, 1991.
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United States. National Aeronautics and Space Administration., ed. Thermoelastic theory for the response of materials functionally graded in two directions with applications to the free-edge problem. [Washington, DC]: National Aeronautics and Space Administration, 1995.
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Boero, Mauro, and Masaru Tateno. Quantum-theoretical approaches to proteins and nucleic acids. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.17.
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This article describes quantum methods used to study proteins and nucleic acids: Hartree–Fock all-electron approaches, density-functional theory approaches, and hybrid quantum-mechanics/molecular-mechanics approaches. In addition to an analysis of the electronic structure, quantum-mechanical approaches for simulating proteins and nucleic acids can elucidate the cleavage and formation of chemical bonds in biochemical reactions. This presents a computational challenge, and a number of methods have been proposed to overcome this difficulty, including enhanced temperature methods such as high-temperature molecular dynamics, parallel tempering and replica exchange. Alternative methods not relying on the knowledge a priori of the final products make use of biasing potentials to push the initial system away from its local minimum and to enhance the sampling of the free-energy landscape. This article considers two of these biasing techniques, namely Blue Moon and metadynamics.
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Clarke, Andrew. Temperature and its measurement. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199551668.003.0003.
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Temperature is that property of a body which determines whether it gains or loses energy in a particular environment. In classical thermodynamics temperature is defined by the relationship between energy and entropy. Temperature can be defined only for a body that is in thermodynamic and thermal equilibrium; whilst organisms do not conform to these criteria, the errors in assuming that they do are generally small. The Celsius and Fahrenheit temperature scales are arbitrary because they require two fixed points, one to define the zero and the other to set the scale. The thermodynamic (absolute) scale of temperature has a natural zero (absolute zero) and is defined by the triple point of water. Its unit of temperature is the Kelvin. The Celsius scale is convenient for much ecological and physiological work, but where temperature is included in statistical or deterministic models, only thermodynamic temperature should be used. Past temperatures can only be reconstructed with the use of proxies, the most important of which are based on isotope fractionation.
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Koblischka, M. R. Growth and Characterization of HTSc Nanowires and Nanoribbons. Edited by A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.11.
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This article describes the fabrication of high-temperature superconducting nanowires and their characterization by magnetic and electric transport measurements. In the literature, nanowires of high-temperature superconductors (HTSc) are obtained by means of lithography, using thin film material as a base. However, there are two main problems with this approach: first, the substrate often influences the HTSc nanowire, and second, only electric transport measurements can be performed. This article explains how nanowires and nanobelts of high-temperature superconducting cuprates can be prepared by the template method and by electrospinning. It also considers the possibilities for employing substrate-free HTSc nanowires as building blocks to realize new, nanoporous bulk superconducting materials for a variety of applications.
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Clarke, Andrew. Principles of Thermal Ecology: Temperature, Energy, and Life. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199551668.001.0001.
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Temperature affects everything. It influences all aspects of the physical environment and governs any process that involves a flow of energy, setting boundaries on what an organism can or cannot do. This novel textbook explores the key principles behind the complex relationship between organisms and temperature, namely the science of thermal ecology. It starts providing a rigorous framework for understanding the nature of temperature and the flow of energy in and out of the organism, before describing the influence of temperature on what organisms can do, and how fast they can do it. Central to this is the relationship between temperature and metabolism, which then forms the basis for an exploration of the effects of temperature on growth and size. Two chapters cover first endothermy (including how this expensive lifestyle might have evolved), and then when and how this is suspended in torpor and hibernation. With these fundamental principles covered, the book’s final section explores thermal ecology itself, incorporating the important extra dimension of interactions with other organisms. After an examination of the relationship between temperature, energy and diversity, an entire chapter is devoted to the crucially important subject of the nature of climate change and how organisms are responding to this. Throughout the book, emphasis is placed on the need for an understanding of the underlying physical mechanisms, and the important insights that can be gained from the historical and fossil record.
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Zhang, H. Mesoscopic Structures and Their Effects on High-Tc Superconductivity. Edited by A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.12.
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This article presents the results of model calculations carried out to determine the mesoscopic structural features of high-temperature superconducting (HTS) crystal structures, and especially their characteristic high critical temperature (Tc) and anisotropy. The crystal structure of high-temperature superconductors (HTSc) is unique in having some mesoscopic features. For example, the structures of a majority of cuprite superconductors are comprised of two structural blocks, perovskite and rock salt, stacked along the c-direction. This article calculates the interaction between the perovskite and rock salt blocks in the form of combinative energy in order to elucidate the effects of mesoscopic structures on high-Tc superconductivity. Both X-ray diffraction and Raman spectroscopy show that a ‘fixed triangle’ exists in the samples under investigation. The article also examines the importance of electron–phonon coupling in high-Tc superconductors.
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Dunlop, Storm. 8. Localized weather. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780199571314.003.0008.
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Although certain weather events, such as violent tornadoes, affect relatively small areas on the ground, there are a number of effects that are localized in their influence. ‘Localized weather’ first considers fog, which may be associated with widespread anticyclonic conditions leading to a significant drop in temperature at night, and relatively quiet, or windless, conditions. The two common forms of fog are radiation fog and advection fog. Haze and smog are also discussed along with local winds divided into two groups: sea, land, and lake breezes; and valley and mountain winds. Katabatic winds, föhn conditions, lake effect snow, ice storms, and glaze (or ‘black ice’) are also considered.
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Segal, David. Disruptive Technologies. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198804079.003.0009.
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Chapter 9 describes potential disruptive technologies in the 21st century. It covers the expanding area of gene editing, also known as genome editing or CRISPR. It describes ‘wonder materials’ such as graphene and high-temperature superconductors. Three-dimensional printing, also known as 3D printing, is covered in the text. Two materials that have intriguing properties, namely metamaterials and auxetic materials and their properties, are described.
Book chapters on the topic "Two-temperature theory"
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Tamma, Kumar K. "Microscale Two-Temperature Theory: Heat Transfer and Constitutive Models." In Encyclopedia of Thermal Stresses, 3019–26. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-2739-7_744.
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Youssef, Hamdy M. "Wave Propagation in the Two-Temperature Theory of Thermoelasticity." In Encyclopedia of Thermal Stresses, 6492–95. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-2739-7_963.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Invisible Thermal Sensors: Bilayer Scheme." In Transformation Thermotics and Extended Theories, 133–47. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_10.
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AbstractIn this chapter, we propose a bilayer scheme with isotropic materials to design invisible thermal sensors with detecting accuracy. Therefore, the original temperature fields in the sensor and matrix can keep unchanged. By solving the linear Laplace equation with a temperature-independent thermal conductivity, we derive two groups of thermal conductivities to realize invisible thermal sensors, even considering geometrically anisotropic cases. These results can be directly extended to thermally nonlinear cases with temperature-dependent thermal conductivity, as long as the ratio between the nonlinear thermal conductivities of the sensor and matrix is a temperature-independent constant. These explorations are beneficial to temperature detection and provide insights into thermal camouflage.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermoelectric Effect Control: Transformation Nonlinear Thermoelectricity." In Transformation Thermotics and Extended Theories, 35–51. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_4.
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AbstractTemperature-dependent (nonlinear) transformation thermotics provides a powerful tool for designing multifunctional, switchable, or intelligent metamaterials in diffusion systems. However, its extension to multiphysics remains studied, in which the temperature dependence of intrinsic parameters is ubiquitous. Here, we theoretically establish a temperature-dependent transformation method for controlling multiphysics. Taking thermoelectric transport as a typical case, we prove the form invariance of its temperature-dependent governing equations and formulate the corresponding transformation rules. Our finite-element simulations demonstrate robust thermoelectric cloaking, concentrating, and rotating performance in temperature-dependent backgrounds. We further design two practical applications with temperature-dependent transformation: an ambient-responsive cloak-concentrator thermoelectric device that can switch between cloaking and concentrating; an improved thermoelectric cloak with nearly-thermostat performance inside. Our theoretical frameworks and application designs may provide guidance for efficiently controlling temperature-related multiphysics and enlighten subsequent intelligent multiphysical metamaterial research.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Wave Nonreciprocity: Angular Momentum Bias." In Transformation Thermotics and Extended Theories, 277–90. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_20.
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AbstractIn this chapter, we demonstrate that an angular momentum bias generated by a volume force can also lead to modal splitting in convection-diffusion systems but with different features. We further reveal the thermal Zeeman effect by studying the temperature field propagation in an angular-momentum-biased ring with three ports (one for input and two for output). With an optimal volume force, temperature field propagation is allowed at one output port but isolated at the other, and the rectification coefficient can reach a maximum value of 1. The volume forces corresponding to the rectification coefficient peaks can also be quantitatively predicted by scalar (i.e., temperature) interference. Compared with existing mechanisms for thermal nonreciprocity, an angular momentum bias does not require temperature-dependent and phase-change materials, which has an advantage in wide-temperature-range applicability. These results may provide insights into thermal stabilization and thermal topology. The related mechanism is also universal for other convection-diffusion systems such as mass transport, chemical mixing, and colloid aggregation.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Diffusive Fizeau Drag: Willis Coupling." In Transformation Thermotics and Extended Theories, 207–17. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_15.
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AbstractIn this chapter, we design a spatiotemporal thermal metamaterial based on heat transfer in porous media to demonstrate the diffusive analog to Fizeau drag. The space-related inhomogeneity and time-related advection enable the diffusive Fizeau drag effect. Thanks to the spatiotemporal coupling, different propagating speeds of temperature fields can be observed in two opposite directions, thus facilitating nonreciprocal thermal profiles. The phenomenon of diffusive Fizeau drag stands robustly even when the advection direction is perpendicular to the propagation of temperature fields. These results could pave an unexpected way toward realizing the nonreciprocal and directional transport of mass and energy.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Invisible Thermal Sensors: Monolayer Scheme." In Transformation Thermotics and Extended Theories, 149–62. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_11.
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AbstractIn this chapter, we propose an anisotropic monolayer scheme to prevent thermal sensors from distorting local and background temperature profiles, making them accurate and thermally invisible. We design metashells with anisotropic thermal conductivity and perform finite-element simulations in two or three dimensions for arbitrarily given thermal conductivity of sensors and backgrounds. We further experimentally fabricate a metashell with an anisotropic thermal conductivity based on the effective medium theory, which confirms the feasibility of our scheme. Our results are beneficial to improving the performance of thermal detection and may also guide other diffusive physical fields.
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Luckhaus, Stephan. "Solutions for the Two-Phase Stefan Problem with the Gibbs—Thomson Law for the Melting Temperature." In Fundamental Contributions to the Continuum Theory of Evolving Phase Interfaces in Solids, 317–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-59938-5_12.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Wave Control: Transformation Complex Thermotics." In Transformation Thermotics and Extended Theories, 19–33. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_3.
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AbstractIn this chapter, we develop a transformation theory for controlling wavelike temperature fields (called thermal waves herein) in conduction and advection. We first unify these two basic heat transfer modes by coining a complex thermal conductivity whose real and imaginary parts are related to conduction and advection. Consequently, the conduction-advection process supporting thermal waves is described by a complex conduction equation, thus called complex thermotics. We then propose the principle for transforming complex thermal conductivities. We further design three metamaterials to control thermal waves with cloaking, concentrating, and rotating functions. Experimental suggestions are also provided based on porous media.
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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Geometric Phases: Exceptional Point Encirclement." In Transformation Thermotics and Extended Theories, 291–304. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_21.
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AbstractIn this chapter, we experimentally demonstrate that the geometric phase can also emerge in a macroscopic thermal convection-conduction system. Following Li et al. [Science 364, 170–173 (2019)], we study two moving rings with equal-but-opposite velocities, joined together by a stationary intermediate layer. We first confirm an exceptional point of velocity that separates a stationary temperature profile and a moving one. We then investigate a cyclic path of time-varying velocity containing the exceptional point, and an extra phase difference of $$\pi $$ π appears (say, the geometric phase). These results broaden the scope of the geometric phase and provide insights into the thermal topology.
Conference papers on the topic "Two-temperature theory"
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Schiller, Arwed, Maxim N. Chernodub, and Ernst-Michael Ilgenfritz. "An Abelian two-Higgs model and high temperature superconductivity." In XXIIIrd International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2005. http://dx.doi.org/10.22323/1.020.0295.
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Nakamura, Yoshifumi, V. G. Bornyakov, Maxim N. Chernodub, Y. Mori, S. M. Morozov, M. I. Polikarpov, G. Schierholz, A. A. Slavnov, H. Stuben, and T. Suzuki. "Critical temperature in QCD with two flavors of dynamical quarks." In XXIIIrd International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2005. http://dx.doi.org/10.22323/1.020.0157.
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Bornyakov, Vitaly. "Finite temperature LQCD with two flavors of improved Wilson fermions." In The XXV International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2008. http://dx.doi.org/10.22323/1.042.0171.
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Lee, Jong-Wan, Biagio Lucini, and Maurizio Piai. "Parity doubling in two-flavor SU(2) at high temperature." In 34th annual International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.256.0080.
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Bornyakov, Vitaly. "Finite temperature phase transition with two flavors of improved Wilson fermions." In The XXVIII International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2011. http://dx.doi.org/10.22323/1.105.0170.
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Itou, Etsuko, Kei Iida, and Tong-Gyu Lee. "Topology of two-color QCD at low temperature and high density." In The 36th Annual International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.334.0168.
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Ferraro, Nate, S. Jardin, B. Lyons, Y. Liu, and C. Kim. "Simulations of Fast Thermal Quenches Using a Two-Temperature Model." In Sherwood Fusion Theory Conference, Princeton, NJ (United States), 15 Apr 2019. US DOE, 2019. http://dx.doi.org/10.2172/1668813.
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Iida, Hideaki, Yu Maezawa, and Koichi Yazaki. "Hadron properties at finite temperature and density with two-flavors of Wilson fermion." In The XXVIII International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2011. http://dx.doi.org/10.22323/1.105.0189.
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Ishiguro, K., Etsuko Itou, and Kei Iida. "Flux tube profiles in two-color QCD at low temperature and high density." In The 38th International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.396.0063.
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Maezawa, Yuu. "Static quark free energies at finite temperature with two flavors of improved Wilson quarks." In XXIVth International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2006. http://dx.doi.org/10.22323/1.032.0141.
Full textReports on the topic "Two-temperature theory"
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Pichersky, Eran, Alexander Vainstein, and Natalia Dudareva. Scent biosynthesis in petunia flowers under normal and adverse environmental conditions. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699859.bard.
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The ability of flowering plants to prosper throughout evolution, and for many crop plants to set fruit, is strongly dependent on their ability to attract pollinators. To that end many plants synthesize a spectrum of volatile compounds in their flowers. Scent is a highly dynamic trait that is strongly influenced by the environment. However, with high temperature conditions becoming more common, the molecular interplay between this type of stress and scent biosynthesis need to be investigated. Using petunia as a model system, our project had three objectives: (1) Determine the expression patterns of genes encoding biosynthetic scent genes (BSGs) and of several genes previously identified as encoding transcription factors involved in scent regulation under normal and elevated temperature conditions. (2) Examine the function of petunia transcription factors and a heterologous transcription factor, PAPl, in regulating genes of the phenylpropanoid/benzenoid scent pathway. (3) Study the mechanism of transcriptional regulation by several petunia transcription factors and PAPl of scent genes under normal and elevated temperature conditions by examining the interactions between these transcription factors and the promoters of target genes. Our work accomplished the first two goals but was unable to complete the third goal because of lack of time and resources. Our general finding was that when plants grew at higher temperatures (28C day/22C night, vs. 22C/16C), their scent emission decreased in general, with the exception of a few volatiles such as vanillin. To understand why, we looked at gene transcription levels, and saw that generally there was a good correlation between levels of transcriptions of gene specifying enzymes for specific scent compounds and levels of emission of the corresponding scent compounds. Enzyme activity levels, however, showed little difference between plants growing at different temperature regimes. Plants expressing the heterologous gene PAPl showed general increase in scent emission in control temperature conditions but emission decreased at the higher temperature conditions, as seen for control plants. Finally, expression of several transcription factor genes decreased at high temperature, but expression of new transcription factor, EOB-V, increased, implicating it in the decrease of transcription of BSGs. The major conclusion of this work is that high temperature conditions negatively affect scent emission from plants, but that some genetic engineering approaches could ameliorate this problem.
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Dzebo, Adis, and Zoha Shawoo. Sustainable Development Goal interactions through a climate lens: a global analysis. Stockholm Environment Institute, February 2023. http://dx.doi.org/10.51414/sei2023.010.
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Interactions between key Sustainable Development Goal (SDG) targets are synergetic at the global level when pursuing efforts to limit the temperature increase to 1.5°C, according to the authors' analysis. Their findings indicate two objectives are most beneficial for making progress on all other targets: making progress on mobilizing climate finance and Official Development Assistance (ODA) and mainstreaming climate change into national policy.
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Casper, Gary, Stefanie Nadeau, and Thomas Parr. Acoustic amphibian monitoring, 2019 data summary: Isle Royale National Park. National Park Service, December 2022. http://dx.doi.org/10.36967/2295506.
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Amphibians are a Vital Sign indicator for monitoring long-term ecosystem health in seven national park units that comprise the Great Lakes Network. We present here the results for 2019 amphibian monitoring at Isle Royale National Park (ISRO). Appendices contain tabular summaries for six years of cumulative results. The National Park Service Great Lakes Inventory and Monitoring Network established 10 permanent acoustic amphibian monitoring sites at ISRO in 2015. Acoustic samples are collected by placing automated recorders with omnidirectional stereo microphones at each of the 10 sampling sites. Temperature loggers co-located with the recorders also collect air temperature during the sampling period. The monitoring program detected all seven species of frog and toad known to occur at ISRO in 2019, with Eastern American Toad, Green Frog and Spring Peeper occurring at almost every site sampled, and Wood Frog at six sites. Gray Treefrog, Mink Frog, and Boreal Chorus Frog were found at only one or two sites each. Northern Leopard Frog has yet to be confirmed at ISRO in this GLKN monitoring program. We expanded analyses and reporting in 2018 to address calling phenology and to provide a second metric for tracking changes in abundance (as opposed to occupancy) across years. Occupancy analyses track whether or not a site was occupied by a species. Abundance is tracked by assessing how the maximum call intensity changes on sites across years, and by how many automated detections are reported from sites across years. Using two independent survey methods, manual and automated, with large sample sizes continues to return reliable results, providing a confident record of site occupancy for most species. There were no significant data collection issues in 2019. Three units stopped collecting data early but these data gaps did not compromise sampling rigor or analysis. Since temperature logs show that the threshold of ≥40°F was often exceeded by 1 April in 2019, making 15 March a start date for data collection may be considered if park personnel feel snow and ice cover would be reduced enough by that date as well. We do recommend making sure that temperature logger solar shields in future are not hanging in such a manner as to be banging against anything in a breeze, as this contaminates the soundscape
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Fuchs, Marcel, Ishaiah Segal, Ehude Dayan, and K. Jordan. Improving Greenhouse Microclimate Control with the Help of Plant Temperature Measurements. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7604930.bard.
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A model of the energy balance of a transpiring crop in a greenhouse was developed in a format suitable for use in climate control algorithms aimed at dissipating excess heat during the warm periods. The model's parameters use external climatic variables as input. It incorporates radiation and convective transfer functions related to the operation of control devices like shading screens, vents, fans and enhanced evaporative cooling devices. The model identified the leaf boundary-layer resistance and the leaf stomatal and cuticular resistance as critical parameters regulating the temperature of the foliage. Special experiments evaluated these variables and established their relation to environmental factors. The research established that for heat load conditions in Mediterranean and arid climates transpiring crops maintained their foliage temperature within the range allowing high productivity. Results specify that a water supply ensuring minimum leaf resistance to remain below 100 s m-1, and a ventilation rate of 30 air exchanges per hour, are the conditions needed to achieve self cooling. Two vegetable crops, tomato and sweet pepper fulfilled maintained their leaf resistance within the prescribed range at maturity, i.e., during the critical warm season. The research evaluates the effects of additional cooling obtained from wet pad systems and spray wetting of foliage.
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Casper, Gary, Stfani Madau, and Thomas Parr. Acoustic amphibian monitoring, 2019 data summary: Mississippi National River and Recreation Area. National Park Service, December 2022. http://dx.doi.org/10.36967/2295507.
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Amphibians are a Vital Sign indicator for monitoring long-term ecosystem health in seven national park units that comprise the Great Lakes Network. We present here the results for 2019 amphibian monitoring at Mississippi National River and Recreation Area (MISS). Appendices contain tabular summaries for six years of cumulative results. The National Park Service Great Lakes Inventory and Monitoring Network established 10 permanent acoustic amphibian monitoring sites at MISS in 2015. Acoustic samples are collected by placing automated recorders with omnidirectional stereo microphones at each of the 10 sampling sites. Temperature loggers co-located with the recorders also collect air temperature during the sampling period. Eight of the nine species of frog and toad known to occur at MISS were found in 2019. The most well distributed species were Eastern American Toad, Gray Treefrog, Green Frog, and Northern Leopard Frog. Rarer are Blanchard’s Cricket Frog, Cope’s Gray Treefrog, Wood Frog, and Boreal Chorus Frog. American Bullfrog has not yet been detected on GLKN monitored sites but has been recently confirmed nearby (Pigs Eye Lake). Two of the ten sites—MISS02, MISS04—were not sampled in 2019 due to flooding, and occupancy of early calling species at MISS06 was determined inconclusive due to a late sampling start. MISS07 was also deployed late and results may contain some false absences due to late sampling. We expanded analyses and reporting in 2018 to address calling phenology and to provide a second metric for tracking changes in abundance (as opposed to occupancy) across years. Occupancy analyses track whether or not a site was occupied by a species. Abundance is tracked by assessing how the maximum call intensity changes on sites across years, and by how many automated detections are reported from sites across years. Using two independent survey methods, manual and automated, with large sample sizes continues to return reliable results, providing a confident record of site occupancy for most species. There were some data collection issues in 2019, with two ARS units not deployed and two others with late start dates. This did reduce our ability to assess some sites and species. Summaries of 2019 data are shown in Appendices A, B and C, and cumulative data collection result summaries are provided in Appendix E. Since temperature logs show that the threshold of ≥40°F was already exceeded by 1 April in 2019, we recommend a 15 March start date for future data collection.
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Lurie, Susan, David R. Dilley, Joshua D. Klein, and Ian D. Wilson. Prestorage Heat Treatment to Inhibit Chilling Injury and Delay Ripening in Tomato Fruits. United States Department of Agriculture, June 1993. http://dx.doi.org/10.32747/1993.7568108.bard.
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The research had two specific goals; (1) to develop and optimize a postharvest heat treatment and characterize the response of tomato to the heat and subsequent cold storage, and (2) to investigate the involvement of heat shock proteins (HSP) in resistance to chilling injury. For the first goal we have investigated many time-temperature treatments using dry heat and found that 48 h at 38oC is optimum for Israeli cultivars, while 48 h at 42oC worked better for American cultivars in preventing chilling injury. We have also compared hot water to hot air and found hot water to be effective, but less so than hot air. Membrane lipid composition in relation to chilling injury was investigated after hot water and hot air treatments. Investigation of fruit ripening found that mRNAs of ripening-related genes were inhibited by high temperature, but recovered during the subsequent storage period and allowed normal ripening to proceed. Sensory studies showed no difference in the taste of heated or nonheated fruit. Following the production of HSP in heated and stored fruit allowed us to determine that during low temperature storage the HSP remained present in the fruit tissue, and their presence was correlated with resistance to chilling injury. HSP clones have been isolated by both differential screening of a cDNA library of heated and chilled tomatoes (Israel) and by mRNA differential display (United States). These clones are being characterized.
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Ruosteenoja, Kimmo. Applicability of CMIP6 models for building climate projections for northern Europe. Finnish Meteorological Institute, September 2021. http://dx.doi.org/10.35614/isbn.9789523361416.
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In this report, we have evaluated the performance of nearly 40 global climate models (GCMs) participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6). The focus is on the northern European area, but the ability to simulate southern European and global climate is discussed as well. Model evaluation was started with a technical control; completely unrealistic values in the GCM output files were identified by seeking the absolute minimum and maximum values. In this stage, one GCM was rejected totally, and furthermore individual output files from two other GCMs. In evaluating the remaining GCMs, the primary tool was the Model Climate Performance Index (MCPI) that combines RMS errors calculated for the different climate variables into one index. The index takes into account both the seasonal and spatial variations in climatological means. Here, MCPI was calculated for the period 1981—2010 by comparing GCM output with the ERA-Interim reanalyses. Climate variables explored in the evaluation were the surface air temperature, precipitation, sea level air pressure and incoming solar radiation at the surface. Besides MCPI, we studied RMS errors in the seasonal course of the spatial means by examining each climate variable separately. Furthermore, the evaluation procedure considered model performance in simulating past trends in the global-mean temperature, the compatibility of future responses to different greenhouse-gas scenarios and the number of available scenario runs. Daily minimum and maximum temperatures were likewise explored in a qualitative sense, but owing to the non-existence of data from multiple GCMs, these variables were not incorporated in the quantitative validation. Four of the 37 GCMs that had passed the initial technical check were regarded as wholly unusable for scenario calculations: in two GCMs the responses to the different greenhouse gas scenarios were contradictory and in two other GCMs data were missing from one of the four key climate variables. Moreover, to reduce inter-GCM dependencies, no more than two variants of any individual GCM were included; this led to an abandonment of one GCM. The remaining 32 GCMs were divided into three quality classes according to the assessed performance. The users of model data can utilize this grading to select a subset of GCMs to be used in elaborating climate projections for Finland or adjacent areas. Annual-mean temperature and precipitation projections for Finland proved to be nearly identical regardless of whether they were derived from the entire ensemble or by ignoring models that had obtained the lowest scores. Solar radiation projections were somewhat more sensitive.
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Blum, Abraham, Henry T. Nguyen, and N. Y. Klueva. The Genetics of Heat Shock Proteins in Wheat in Relation to Heat Tolerance and Yield. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568105.bard.
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Fifty six diverse spring wheat cultivars were evaluated for genetic variation and heritability for thermotolerance in terms of cell-membrane stability (CMS) and triphenyl tetrazolium chloride (TTC) reduction. The most divergent cultivars for thermotolerance (Danbata-tolerant and Nacozari-susceptible) were crossed to develop an F8 random onbred line (RIL) population. This population was evaluated for co-segragation in CMS, yield under heat stress and HSP accumulation. Further studies of thermotolerance in relations to HSP and the expression of heterosis for growth under heat stress were performed with F1 hybrids of wheat and their parental cultivars. CMS in 95 RILs ranged from 76.5% to 22.4% with 71.5% and 31.3% in Danbata and Nacozari, respectively. The population segregated with a normal distribution across the full range of the parental values. Yield and biomass under non-stress conditions during the normal winter season at Bet Dagan dit not differ between the two parental cultivar, but the range of segregation for these traits in 138 RILs was very high and distinctly transgressive with a CV of 35.3% and 42.4% among lines for biomass and yield, respectively. Mean biomass and yield of the population was reduced about twofold when grown under the hot summer conditions (irrigated) at Bet Dagan. Segregation for biomass and yield was decreased relative to the normal winter conditions with CV of 20.2% and 23.3% among lines for biomass and yield, respectively. However, contrary to non-stress conditions, the parental cultivars differed about twofold in biomass and yield under heat stress and the population segregated with normal distribution across the full range of this difference. CMS was highly and positively correlated across 79 RILs with biomass (r=0.62**) and yield (r=0.58**) under heat stress. No such correlation was obtained under the normal winter conditions. All RILs expressed a set of HSPs under heat shock (37oC for 2 h). No variation was detected among RILs in high molecular weight HSP isoforms and they were similar to the patterns of the parental cultivars. There was a surprisingly low variability in low molecular weight HSP isoforms. Only one low molecular weight and Nacozari-specific HSP isoform (belonging to HSP 16.9 family) appeared to segregate among all RILs, but it was not quantitatively correlated with any parameter of plant production under heat stress or with CMS in this population. It is concluded that this Danbata/Nacozari F8 RIL population co-segregated well for thermotolerance and yield under heat stress and that CMS could predict the relative productivity of lines under chronic heat stress. Regretfully this population did not express meaningful variability for HSP accumulation under heat shock and therefore no role could be seen for HSP in the heat tolerance of this population. In the study of seven F1 hybrids and their parent cultivars it was found that heterosis (superiority of the F1 over the best parent) for CMs was generally lower than that for growth under heat stress. Hybrids varied in the rate of heterosis for growth at normal (15o/25o) and at high (25o/35o) temperatures. In certain hybrids heterosis for growth significantly increased at high temperature as compared with normal temperature, suggesting temperature-dependent heterosis. Generally, under normal temperature, only limited qualitative variation was detected in the patterns of protein synthesis in four wheat hybrids and their parents. However, a singular protein (C47/5.88) was specifically expressed only in the most heterotic hybrid at normal temperature but not in its parent cultivars. Parental cultivars were significantly different in the sets of synthesized HSP at 37o. No qualitative changes in the patterns of protein expression under heat stress were correlated with heterosis. However, a quantitative increase in certain low molecular weight HSP (mainly H14/5.5 and H14.5.6, belonging to the HSP16.9 family) was positively associated with greater heterosis for growth at high temperature. None of these proteins were correlated with CMS across hybrids. These results support the concept of temperature-dependent heterosis for growth and a possible role for HSP 16.9 family in this respect. Finally, when all experiments are viewed together, it is encouraging to find that genetic variation in wheat yield under chronic heat stress is associated with and well predicted by CMS as an assay of thermotolerance. On the other hand the results for HSP are elusive. While very low genetic variation was expressed for HSP in the RIL population, a unique low molecular weight HSP (of the HSP 16.9 family) could be associated with temperature dependant heterosis for growth.
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Yahav, Shlomo, John Brake, and Noam Meiri. Development of Strategic Pre-Natal Cycling Thermal Treatments to Improve Livability and Productivity of Heavy Broilers. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7593395.bard.
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The necessity to improve broiler thermotolerance and live performance led to the following hypothesis: Appropriate comprehensive incubation treatments that include significant temperature management changes will promote angiogenesis and will improve acquisition of thermotolerance and carcass quality of heavy broilers through epigenetic adaptation. It was based on the following questions: 1. Can TM during embryogenesis of broilers induce a longer-lasting thermoregulatory memory (up to marketing age of 10 wk) that will improve acquisition of thermotolerance as well as increased breast meat yield in heavy broilers? 2. The improved sensible heat loss (SHL) suggests an improved peripheral vasodilation process. Does elevated temperature during incubation affect vasculogenesis and angiogenesis processes in the chick embryo? Will such create subsequent advantages for heavy broilers coping with adverse hot conditions? 3. What are the changes that occur in the PO/AH that induce the changes in the threshold response for heat production/heat loss based on the concept of epigenetic temperature adaptation? The original objectives of this study were as follow: a. to assess the improvement of thermotolerance efficiency and carcass quality of heavy broilers (~4 kg); b. toimproveperipheral vascularization and angiogenesis that improve sensible heat loss (SHL); c. to study the changes in the PO/AH thermoregulatory response for heat production/losscaused by modulating incubation temperature. To reach the goals: a. the effect of TM on performance and thermotolerance of broilers reared to 10 wk of age was studied. b. the effect of preincubation heating with an elevated temperature during the 1ˢᵗ 3 to 5 d of incubation in the presence of modified fresh air flow coupled with changes in turning frequency was elucidated; c.the effect of elevated temperature on vasculogenesis and angiogenesis was determined using in ovo and whole embryo chick culture as well as HIF-1α VEGF-α2 VEGF-R, FGF-2, and Gelatinase A (MMP2) gene expression. The effects on peripheral blood system of post-hatch chicks was determined with an infrared thermal imaging technique; c. the expression of BDNF was determined during the development of the thermal control set-point in the preoptic anterior hypothalamus (PO/AH). Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” Recently, Piestunet al. (2008) demonstrated for the first time that TM (an elevated incubation temperature of 39.5°C for 12 h/d from E7 to E16) during the development/maturation of the hypothalamic-hypophyseal-thyroid axis (thermoregulation) and the hypothalamic-hypophyseal-adrenal axis (stress) significantly improved the thermotolerance and performance of broilers at 35 d of age. These phenomena raised two questions that were addressed in this project: 1. was it possible to detect changes leading to the determination of the “set point”; 2. Did TM have a similar long lasting effect (up to 70 d of age)? 3. Did other TM combinations (pre-heating and heating during the 1ˢᵗ 3 to 5 d of incubation) coupled with changes in turning frequency have any performance effect? The improved thermotolerance resulted mainly from an efficient capacity to reduce heat production and the level of stress that coincided with an increase in SHL (Piestunet al., 2008; 2009). The increase in SHL (Piestunet al., 2009) suggested an additional positive effect of TM on vasculogenesis and angiogensis. 4. In order to sustain or even improve broiler performance, TM during the period of the chorioallantoic membrane development was thought to increase vasculogenesis and angiogenesis providing better vasodilatation and by that SHL post-hatch.
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Yahav, Shlomo, John Brake, and Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, September 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
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: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.